(a) Liquid ammonia can be used as a refrigerant, as an alternative for chlorofluorocarbons.
The main refrigerants used are Freon chlorofluorocarbons (CFC). They deplete ozone layer. The chlorofluorocarbons are decomposed by ultraviolet rays to highly reactive chlorine which is produced in the atomic form.
The free *** [Cl] reacts with ozone and chlorine monoxide is formed.
Cl(g) + O (g) → ClO(g) + O (g)
This causes depletion of ozone layer and chlorine monoxide so formed reacts with atomic oxygen and produces more chlorine free ****.
ClO + O → Cl + O2
Again this free *** destroys ozone and the process continues thereby giving rise to ozone depletion.
(b) Advantages of ammonia as refrigerant:
(i) Ammonia is environmentally compatible. It does not deplete ozone layer and does not contribute towards global warming.
(ii) It has superior thermodynamic qualities as a result ammonia refrigeration systems use less electricity.
Ammonia has a recognizable odour and so leaks are not likely to escape.
